Author Paul Greenberg wants the seafood consumer to take a deeper look into what they purchase. More than 80 per cent of the seafood that Americans consume is imported. It didn’t use to be like that.

Mr. Greenberg spoke at The Tabernacle in Oak Bluffs on Monday night as part of the Martha’s Vineyard Camp Meeting Association’s summer program of speakers and performers. Mr. Greenberg is the author of Four Fish and American Catch, The Fight for Our Local Seafood. A key ingredient of his talk was his concern that the country is out of touch with the problems faced by the fishing industry, along with the loss of fish and their habitat.

Though the United States controls more ocean than any other country in the world, Mr. Greenberg noted at the opening of his talk, we aren’t very good at taking care of what was once a most valued resource. So much of the seafood consumed in this country is now imported. Even the fish harvested in this country is shipped overseas for processing and often re-frozen and repacked and shipped back.

Mr. Greenberg described himself as an avid angler, one who loves to fish and who has spent many summers vacationing on the Vineyard. He recalled catching squeteague, also called weakfish, while fishing on the Island and meeting Everett Poole.

Mr. Greenberg told the story of how he became interested in writing about fish after moving to New York city. While living in lower Manhattan he became fascinated with how New York was once New Amsterdam, a major fishing port. Residents of that small community harvested fish and shellfish from the Hudson River and beyond. He described how the consumption of seafood was a key to the building of the city and sustaining it. He spoke of striped bass swimming in the East River, and of oysters being harvested in the nearby estuaries not by the bushel, but by the barrel.

At one point, New York city was synonymous with the oyster. Mr. Greenberg said that early in the 1900s the city produced 1.4 billion oysters a year. But oysters are fragile, and the fishery declined as the city dumped more and more raw sewage into its waters.

While the country has grown, its estuaries have diminished, which are the source of both shellfish and finfish, he said.

“We traded our estuaries for the estuaries of other countries,” he said.

Pollock, a fish once common to these waters, is now heavily fished in the waters of Alaska. Mr. Greenberg reported that pollock is shipped from the United States to China where it is refrozen and shipped back to the United States for consumption.

Tilapia, a tropical fish that grows quickly, is packaged in the orient and shipped to this country, where it is rebranded to make it look like it comes from Gloucester.

At the end of the program, Mr. Greenberg was asked what seafood he recommends.

“Eat American,” he said. “Second, eat a broader variety of fish.”

His third recommendation was to pay attention to local aquaculture. This, he said, is to be encouraged as it helps in the restoration of habitat.

“They are the filter feeders,” he said, referring to shellfish. Any effort to support aquaculture helps with the restoration of local waters.